There has been no official word from AdSense at present, so i would guess this feature is currently in testing and they are going to be monitoring what effect this has on CTR and what publishers/advertisers think about it.
initial responses seem positive, Nobody has complained about it and many have said the italic font on AdSense ads is "eye catching".
This may demonstrate a positive aspect of "ad blindness", Ad blindness also means very small changes to how the ads are displayed could have a large impact on how noticeable the ads are. Because we are used to seeing the same ad format over and over again if that format is changed, Even slightly, It may mean people suffering ad blindness have their attention drawn towards the changes.
It also may be the beginning of a new era where AdSense allows publishers to pick exactly how their ads are displayed, I wouldn't be surprised if soon advertisers are able to pick what font their ad is displayed in.
Have any AdWords advertisers seen an option in their control panel to have their ads displayed in italic font? Or does anyone have a screen shot of this new italic font format?